You can switch although you'll want to save things like pictures, documents, music, etc. as you will have to format and erase the drive before linux can be installed.
You should also make sure there aren't any windows programs you need as programs that run on windows are not compatible with linux unless that company releases a version specifically for linux in addition to the windows versions. You can usually find a linux alternative to most windows programs.
Its very easy to do!
First, welcome to the world of Linux! For starters, there will be no command lines, and the install is very guided. Its very similar to a game, if you wish to compare it like that. Just point and click.
I highly recommend Linux Mint.
All you have to do, is burn the CD so it is bootable (just google "make linux mint cd"), and then go into your boot menu and have it boot from the CD drive. I"m not sure what it is for your laptop, but when you get the BIOS splash screen, just hit F12. Then choose the CD drive. The rest will be very guided.
Come back if you need help!
I have two Aspire Ones, one Linux and one Windows XP. The Aspire One with Windows is a much beefier machine than the Linux-native model. The only real problem will be in getting the appropriate drivers for things like the sound card and smart card readers under Linux. If you use a lot of peripherals, take time to investigate whether those peripherals will still work after you migrate.
Linpus Linux is what shipped on the Linux native model, and to be actually useful, it must be "rooted" similar to a smartphone. Frankly, I was not impressed by it. The more robust Windows model should be able to run any version of Linux. You also can install Linux from a memory stick, thus eliminating the need for an external CD drive.
A few web searches (I used "acer one migrate from windows to linux") will give you more specific information such as: